Taxonomy of Banksia
Increasingly, molecular evidence from DNA is providing important new insights into relationships within the genus and between this and other genera in the Proteaceae.
The most recent complete revision is that published in Alex George's 1999 monograph for the Flora of Australia book series; this recognises two subgenera, three sections, 13 series, 77 species, 6 subspecies and 18 varieties, and treats the traditionally related genus Dryandra as separate but closely related.
Recent molecular cladistic analyses have provided an alternative view in which Dryandra is shown to be nested inside, and hence should be included within, Banksia.
Banksia (in the traditional sense, not including Dryandra), is a genus of around 80 species in the plant family Proteaceae.
An iconic Australian wildflower and popular garden plant, they are easily recognised by their characteristic flower spikes and fruiting "cones".
They grow in forms varying from prostrate woody shrubs to trees up to 35 metres tall, and occur in all but the most arid areas of Australia.
Specimens of Banksia were first collected by Sir Joseph Banks and Dr Daniel Solander, naturalists on the Endeavour during Lieutenant (later Captain) James Cook's first voyage to the Pacific Ocean.
In June the ship was careened at Endeavour River, where specimens of B. dentata (Tropical Banksia) were collected.
On the Endeavour's return to England in July 1771, Banks' specimens became part of his London herbarium, and artists were employed to paint watercolours from Parkinson's sketches.
Linnaeus placed the genus in class Tetrandra, order Monogynia of his father's classification,[3] and named it in honour of Banks.
However Linnaeus incorrectly attributed the Forsters' specimens to the genus Passerina, and therefore considered the name Banksia available for use.
[5] In 1810, Robert Brown published descriptions and a taxonomic arrangement of the 31 known species of Banksia in his Prodromus Florae Novae Hollandiae et Insulae Van Diemen.
Banksia is placed subtribe Banksiinae on a number of grounds of which the most obvious and easily recognised is the occurrence of flowers in condensed heads.
[12][13] This has been put into effect in a 2007 paper by Mast & Thiele, in which all existing species of Dryandra were transferred into Banksia.
George's arrangement was based on a variety of properties including leaf, style, pollen-presenter, follicle and seed characters, with the criterion that a taxon was considered a distinct species only if it exhibited a "significant and consistent difference in the morphology of flowers and/or fruit".
[6] This conventional taxonomic arrangement of Banksia, as provided by George and published in the Flora of Australia series, may be summarised as follows: In 1996, Kevin Thiele and Pauline Ladiges published a cladistic analysis of the genus Banksia in the journal Australian Systematic Botany.
He stated that "the infrageneric classification and systematic sequence presented here are modified from that of George (1981) and take into account new data revealed in the work of Thiele & Ladiges (1996)", but none of the four promotions to species rank was accepted, and none of the thirteen infrageneric taxa introduced by Thiele and Ladiges was retained.
[9] However, a number of Australian herbaria have continued to follow Thiele and Ladiges on some points, for example by recognising the four species that they promoted.
These taxa are typically tall shrubs and trees that occur in moist areas; they have unbeaked follicles and soft, short-lived leaves that are in many cases needle-like.
Thus, the results presented by Mast et al. strongly suggest that Banksia is paraphyletic with respect to Dryandra.
